Wash the potatoes and cook in boiling water for about 25 minutes. In the meantime clean and wash broccoli, cut off florets and cook in boiling salted water for about 4 minutes. Pour into a sieve, rinse cold and drain well
Drain the potatoes, rinse and peel. Press the hot potatoes through a potato ricer. Season with salt, pepper and nutmeg. Stir in semolina immediately with a mixing spoon. Let the potato mixture cool down a little. Stir in starch and egg yolk and let it cool down completely
Form potato dough into rolls on a floured work surface. Cut into pieces. Form about 40 small oval dumplings. Press one side slightly with a fork
Place 2-3 portions in plenty of boiling salted water. Cook over low to medium heat for 5-7 minutes (do not boil). Remove the gnocchi with a skimmer and drain well
Wash basil, shake dry, pluck leaves from the stalks and chop. Coarsely grate the cheese. Mix stock, cream and cheese. Season to taste with salt, pepper and basil, except for a little bit for sprinkling
Place the gnocchi and broccoli in a greased casserole dish. Spread the pesto in patches on top. Pour the cream mixture over them and bake in a preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 25 minutes. Sprinkle the finished casserole with basil